fix(i18n): sweep hardcoded 'en-US' from non-loyalty JS to I18n.locale

Follow-up to dd1f9af8 which fixed loyalty. The same hardcoded 'en-US'
in toLocaleDateString / toLocaleString / Intl.NumberFormat appeared in
13 files across catalog, marketplace, orders, tenancy, inventory,
monitoring, cms, the storefront layout, and the shared Utils helper
itself. After this sweep, no non-loyalty JS hardcodes 'en-US' anymore;
all use I18n.locale and respect the user's dashboard language.

The highest-leverage one is static/shared/js/utils.js (Utils.formatDate
/ Utils.formatDateTime / Utils.formatCurrency / Utils.formatNumber) —
those four helpers are called from across the frontends so this one
edit fixes most secondary callsites for free.

Codemod scope was conservative: only replaced 'en-US' when it
appeared as the first argument to toLocale* or new Intl.* calls, to
avoid touching unrelated occurrences (none found, but the guard
matters if more get added).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/modules/cms/static/admin/js/content-pages.js

@@ -272,7 +272,7 @@ function contentPagesManager() {
             } else if (diffDays < 7) {
                 return `${diffDays} days ago`;
             } else {
-                return date.toLocaleDateString('en-US', {
+                return date.toLocaleDateString(I18n.locale, {
                     year: 'numeric',
                     month: 'short',
                     day: 'numeric'